Table II.C1 presents key demographic, economic, and programmatic assumptions for three alternative scenarios. The intermediate assumptions reflect the Trustees’ best estimates of future experience. Therefore, most of the figures in this overview present outcomes under the intermediate assumptions only. Any projection of the future is, of course, uncertain. For this reason, the Trustees also present results under low-cost and high-cost alternatives to provide a range of possible future experience. The actual future costs are unlikely to be as extreme as those portrayed by the low-cost or high-cost projections. A separate section on the uncertainty of the projections, beginning on page 17, highlights the implications of these alternative scenarios.